Fan structure

ABSTRACT

A fan structure includes a frame having an inner surface, a permeable element covering the inner surface of the frame, a coil surrounded by the permeable element and a rotor assembly disposed rotatably in the frame. The rotor assembly includes a plurality of blades coupled to a shaft and a permanent magnet enclosing the blades and facing the coil. The rotor assembly rotates along the shaft to generate airflow by means of the electromagnetic effect between the permanent magnet and the coil.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application claims priority of Taiwan Patent Application No. 099123377, filed on Jul. 16, 2010, the entirety of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a fan structure, and in particular, to a fan structure having a frame with a permeable stator structure therein to strengthen the frame.

2. Description of the Related Art

Usually, the frame of a traditional fan structure is made of plastics. Due to minimal structural rigidity of plastic frames, extrinsic forces may easily cause the frame to generate resonance. To prevent structural resonance, two solutions have been disclosed. One solution is to change the material of the frame to enhance structural rigidity and restrain vibration (for example, the frame can be made from aluminum). However, the manufacturing costs would be increased. Another solution is to change the cogging torque of the motor by using a three-phase motor. However, it is only to change vibration frequency of the fan structure (e.g. four times frequency changes to twelve times frequency). Thus, structural resonance is not entirely prevented.

BRIEF SUMMARY OF THE INVENTION

Accordingly, the invention provides a fan structure having a frame with a permeable stator structure therein to strengthen the frame and hinder vibrations thereof. A coil winding method of a slotless motor is used to form a slotless motor structure with a stator on an outer side and a rotor in an inner side of the stator. Therefore, a cogging torque can be eliminated and vibration of the fan structure can be decreased.

In a preferred embodiment, the fan structure of the present invention includes a frame, a permeable element, a coil and a rotor assembly. The frame has an inner surface. The permeable element covers the inner surface of the frame. The coil is surrounded by the permeable element. The rotor assembly is rotatably disposed in the frame. The rotor assembly includes a plurality of blades and a permanent magnet. The blades are coupled to a shaft. The permanent magnet encloses the blades and faces the coil. The rotor assembly rotates about the shaft to generate airflow by means of the electromagnetic effect between the permanent magnet and the coil.

In the above preferred embodiment, the size of an outer peripheral surface of the coil corresponds to the size of an inner peripheral surface of the permeable element.

In the above preferred embodiment, the coil is in an annular shape and the inner peripheral surface of the permeable element is tubular, and the outer diameter of the coil corresponds to the inner diameter of the permeable element.

In the above preferred embodiment, the outer peripheral surface of the coil abuts the inner peripheral surface of the permeable element.

In the above preferred embodiment, the permanent magnet is in an annular shape and faces an inner side of the coil.

In the above preferred embodiment, outer edges of the blades are connected to a peripheral ring, and the permanent magnet is connected to the peripheral ring and rotates along the shaft.

In the above preferred embodiment, the rotor assembly further includes an iron ring disposed between the peripheral ring and the permanent magnet.

In the above preferred embodiment, the fan structure further comprises a sleeve and a bearing received in the sleeve for supporting the shaft.

In the above preferred embodiment, the peripheral ring, the blades and the sleeve are formed as a single piece.

In the above preferred embodiment, the permeable element is a silicon steel plate set, and the permeable element is formed with the frame as a single piece. The frame covers the silicon steel plate set by injection molding, and the frame is made from a permeable material or plastic material.

In another preferred embodiment, the fan structure of the present invention includes a frame, a coil and a rotor assembly. The frame is made from permeable material and has an inner surface. The coil is surrounded by the inner surface of the frame. The rotor assembly is rotatably disposed in the frame. The rotor assembly includes a plurality of blades and a permanent magnet. The blades are coupled to a shaft. The permanent magnet encloses the blades and faces the coil. The rotor assembly rotates about the shaft to generate air flow by means of an electromagnetic effect between the permanent magnet and the coil.

In the above preferred embodiment, the size of an outer peripheral surface of the coil corresponds to the size of the inner surface of the frame.

In the above preferred embodiment, the coil is in an annular shape, and the outer diameter of the coil corresponds to the inner diameter of the frame.

In the above preferred embodiment, the outer peripheral surface of the coil abuts the inner surface of the frame.

In the above preferred embodiment, the permanent magnet is in an annular shape and faces an inner side of the coil.

In the above preferred embodiment, outer edges of the blades are connected to a peripheral ring of the fan structure, and the permanent magnet is connected to the peripheral ring and rotates along the shaft.

In the above preferred embodiment, the permanent magnet is connected to the peripheral ring by a tight fit.

In the above preferred embodiment, the rotor assembly further includes an iron ring disposed between the peripheral ring and the permanent magnet.

In the above preferred embodiment, the fan structure further comprises a sleeve and a bearing received in the sleeve for supporting the shaft.

In the above preferred embodiment, the peripheral ring, the blades and the sleeve are formed as a single piece.

In the above preferred embodiment, the coil is made by a winding method, which is the same as the winding method used by a three-phase slotless motor.

In conclusion, the frame of the present invention is made from plastic, and the silicon steel plate set is incorporated in the plastic frame. Hence, the frame of the present invention has great rigidity, like that of a metal frame, and great resiliency, like that of a plastic frame. Also, rigidity of the frame can hinder vibrations thereof. Meanwhile, because of the plastic frame, its appearance can be designed more beautifully and creatively.

Again, the rigidity of the frame can hinder vibrations thereof, because the frame is made from permeable material containing a high percentage of metal.

The frame of the present invention is a part of a stator thereof, and hence the stator is located at the outer side of the rotor assembly and the rotor assembly is located at the inner side of the stator. In the present invention, because the inner space of the sleeve is only used to receive the shaft and the bearing therein, the size of the sleeve becomes smaller, and the size of the blades can be larger. Therefore, the area of the airflow outlet can be maximized and hence the airflow output from the fan structure can be increased.

Because the silicon steel plate set and the frame made of permeable material do not have the teeth structure, a winding method of the three-phase slotless motor can be utilized for the coil to let the outer diameter of the coil correspond to the inner diameter of the silicon steel plate set as the slotless motor according to the present invention. Therefore, the cogging torque is not generated. Also, the silicon steel plate set has a permeance function to make the motor have a closed magnetic circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIG. 1 is an exploded view of an embodiment of the fan structure of the present invention;

FIG. 2 is a plane view of an assembled fan structure according to FIG. 1;

FIG. 3 is a cross-sectional view of FIG. 2 along the line AA′;

FIG. 4 is a plane view of another embodiment of the fan structure of the present invention; and

FIG. 5 is a cross-sectional view of FIG. 4 along the line BB′.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is an exploded view of an embodiment of a fan structure of the present invention. FIG. 2 is a plane view of an assembled fan structure according to FIG. 1. FIG. 3 is a cross-sectional view of FIG. 2 along the line AA′. As shown in FIGS. 1, 2 and 3, the fan structure 100 of the present invention includes a frame 10, a silicon steel plate set (permeable element) 20, a coil 30, a permanent magnet 40, an iron ring 50 and a fan 60. The frame 10, the silicon steel plate set 20 and the coil 30 constitute a stator of the fan structure 100, and the permanent magnet 40, the iron ring 50 and the fan 60 are formed as a rotor assembly. The structure of the stator is described below.

The silicon steel plate set 20 is made from a plurality of arranged silicon steel plates by stamping. After the stamping process, the silicon steel plate set 20 is disposed in a mold of an injection-molding machine. Then, the molding material is injected into the mold to form the frame 10, wherein the frame 10 and the silicon steel plate set 20 are formed as a monolithic piece. In this embodiment, the molding material can be plastic. Thus, the strength of the frame 10 can be increased because of the combination of the silicon steel plate set 20 and the frame 10. The silicon steel plate set 20 can be fixed by the molding material of the frame 10. After the frame 10 and the silicon steel plate set 20 are formed as a single piece, the inner surface 12 of the frame 10 (as shown in FIG. 3) is covered by the silicon steel plate set 20.

The coil 30 is made by a winding method of the three-phase slotless motor. The coil 30 is formed in an annular shape. The coil 30 is surrounded by an inner peripheral surface 22 of the silicon steel plate set 20. The size of the outer peripheral surface of the coil 30 corresponds to the size of the inner peripheral surface 22 of the silicon steel plate set 20. Because the inner peripheral surface 22 of the silicon steel plate set 20 is tubular, the outer diameter of the outer peripheral surface of the coil 30 is substantially equal to or corresponds to the inner diameter of the inner peripheral surface 22 of the silicon steel plate set 20.

The structure of the rotor assembly including the permanent magnet 40, the iron ring 50 and the fan 60 is described below.

The fan 60 includes a peripheral ring 62 and a plurality of blades 64. Outer edges of the blades 64 are connected to the peripheral ring 62. Inner edges of the blades 64 are connected to a sleeve 66. Please refer to FIG. 3, wherein a bearing 70 is disposed in the sleeve 66. The bearing 70 is used to support the shaft 80. By the structures described above, the fan 60 can rotate about the shaft 80. The sleeve 66, the blades 64 and the peripheral ring 62 are formed as a single piece.

The permanent magnet 40 is formed in an annular shape, and is connected to the peripheral ring 62 of the fan 60 by a tight fit. An outer peripheral surface of the permanent magnet 40 faces the inner side of the coil 30.

By the structure described above, when the power is supplied to the coil 30, the rotor assembly rotates and drives the blades 64 to rotate about the shaft 80 to generate airflow by means of the electromagnetic effect between the permanent magnet 40 and the coil 30.

Furthermore, the iron ring 50 can be disposed between the permanent magnet 40 and the outer peripheral surface 62 of the fan 60 to increase magnetic conductivity. In another embodiment, the iron ring 50 can be omitted.

FIG. 4 is a plane view of another embodiment of the fan structure of the present invention. FIG. 5 is a cross-sectional view of FIG. 4 along the line BB′. In this embodiment, the fan structure 200 includes a frame 210, a coil 230, a permanent magnet 240, an iron ring 250 and a fan 260. The frame 210 and the coil 230 constitute a stator of the fan structure. The permanent magnet 240, the iron ring 250 and the fan 260 constitute a rotor assembly. The structure of the stator is described below.

The frame 210 is made from permeable material. The frame 210 has enough strength, because rigidity of the permeable material is great.

The coil 230 is made by a winding method of the three-phase slotless motor. The coil 230 is formed in an annular shape. The coil 230 is surrounded by an inner surface 212 of the frame 210. The size of an outer peripheral surface of the coil 230 corresponds to the size of the inner surface 212 of the frame 210. The inner surface 212 of the frame 210 is tubular, and hence the outer diameter of the outer peripheral surface of the coil 230 is substantially equal to and corresponds to the inner diameter of the inner surface 212 of the frame 210.

The structure of the rotor assembly including the permanent magnet 240, the iron ring 250 and the fan 260 is described below.

The fan 260 includes a peripheral ring 262 and a plurality of blades 264. Outer edges of the blades 264 are connected to the peripheral ring 262. Inner edges of the blades 264 are connected to a sleeve 266. A bearing 270 is disposed in the sleeve 266. The bearing 270 is used to support the shaft 280. By the structures described above, the fan 260 can rotate about the shaft 280. The sleeve 266, the blades 264 and the peripheral ring 262 can be formed as a monolithic piece.

The permanent magnet 240 is formed in an annular shape and connected to the peripheral ring 262 of the fan 260 by a tight fit. The outer peripheral surface of the permanent magnet 240 faces the inner side of the coil 230.

By the structure described above, when power is supplied to the coil 30, the rotor assembly rotates and drives the blades 264 to rotate about the shaft 280 to generate airflow by means of the electromagnetic effect between the permanent magnet 240 and the coil 230.

Furthermore, the iron ring 250 can be disposed between the permanent magnet 240 and the outer peripheral surface 262 of the fan 260 to increase the magnetic conductivity. In another embodiment, the iron ring 250 can be omitted.

In conclusion, the frame of the present invention is made from plastic and the silicon steel plate set is incorporated in the plastic frame. Hence, the frame of the present invention has great rigidity, like that of a metal frame, and great resiliency, like that of a plastic frame. Also, rigidity of the frame can hinder vibrations thereof. Meanwhile, because of the plastic frame, its appearance can be designed more beautifully and creatively.

Again, the rigidity of the frame can hinder vibrations thereof, because the frame is made from permeable material containing a high percentage of metal.

The frame of the present invention is a part of a stator thereof, and hence the stator is located at the outer side of the rotor assembly and the rotor assembly is located at the inner side of the stator. In the present invention, because the inner space of the sleeve is only used to receive the shaft and the bearing therein, the size of the sleeve becomes smaller, and the size of the blades can be larger. Therefore, the area of the airflow outlet can be maximized and hence the airflow output from the fan structure can be increased.

Because the silicon steel plate set and the frame made of permeable material do not have the teeth structure, a winding method of the three-phase slotless motor can be utilized for the coil to let the outer diameter of the coil correspond to the inner diameter of the silicon steel plate set as the slotless motor according to the present invention. Therefore, the cogging torque is not generated. Also, the silicon steel plate set has a permeance function to make the motor have a closed magnetic circuit.

While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements. 

1. A fan structure comprising: a frame having an inner surface; a permeable element covering the inner surface of the frame; a coil surrounded by the permeable element; and a rotor assembly rotatably disposed in the frame, wherein the rotor assembly comprises: a plurality of blades coupled to a shaft; and a permanent magnet enclosing the blades and facing the coil, wherein the rotor assembly rotates about the shaft to generate air flow by means of the electromagnetic effect between the permanent magnet and the coil.
 2. The fan structure as claimed in claim 1, wherein the size of an outer peripheral surface of the coil corresponds to the size of an inner peripheral surface of the permeable element.
 3. The fan structure as claimed in claim 2, wherein the coil is in an annular shape and the inner peripheral surface of the permeable element is tubular, and the outer diameter of the coil corresponds to the inner diameter of the permeable element.
 4. The fan structure as claimed in claim 3, wherein the outer peripheral surface of the coil abuts the inner peripheral surface of the permeable element.
 5. The fan structure as claimed in claim 3, wherein the permanent magnet is in an annular shape and faces an inner side of the coil.
 6. The fan structure as claimed in claim 5, wherein the blades have a plurality of outer edges connected to a peripheral ring, and the permanent magnet is connected to the peripheral ring and rotates along the shaft.
 7. The fan structure as claimed in claim 6, wherein the rotor assembly further comprises an iron ring disposed between the peripheral ring and the permanent magnet.
 8. The fan structure as claimed in claim 6, further comprising a sleeve and a bearing received in the sleeve for supporting the shaft.
 9. The fan structure as claimed in claim 8, wherein the peripheral ring, the blades and the sleeve are formed as a single piece.
 10. The fan structure as claimed in claim 1, wherein the permeable element is a silicon steel plate set, and the permeable element is formed with the frame as a single piece.
 11. The fan structure as claimed in claim 10, wherein the frame covers the silicon steel plate set by injection molding.
 12. The fan structure as claimed in claim 11, wherein the frame is made from plastic material.
 13. The fan structure as claimed in claim 1, wherein the coil is made by a winding method of the three-phase slotless motor.
 14. The fan structure as claimed in claim 1, wherein the frame is made from a permeable material or a plastic material.
 15. A fan structure comprising: a frame, made from permeable material, having an inner surface; a coil surrounded by the inner surface of the frame; and a rotor assembly rotatably disposed in the frame, wherein the rotor assembly comprises: a plurality of blades coupled to a shaft; and a permanent magnet enclosing to the blades and facing the coil, wherein the rotor assembly rotates about the shaft to generate air flow by means of the electromagnetic effect between the permanent magnet and the coil.
 16. The fan structure as claimed in claim 15, wherein the coil is in an annular shape, and the outer diameter of the coil corresponds to the inner diameter of the frame.
 17. The fan structure as claimed in claim 16, wherein the permanent magnet is in an annular shape and corresponds to an inner side of the coil, and the blades have a plurality of outer edges connected to a peripheral ring of the fan structure, and the permanent magnet connects to the peripheral ring and rotates along the shaft.
 18. The fan structure as claimed in claim 17, wherein the permanent magnet is connected to the peripheral ring by a tight fit.
 19. The fan structure as claimed in claim 18, wherein the rotor assembly further comprises an iron ring disposed between the peripheral ring and the permanent magnet.
 20. The fan structure as claimed in claim 15, wherein the coil is made by a winding method of the three-phase slotless motor. 